1. Field of the Invention
This invention relates to a power line (or power cable) current interrupter having a vacuum switch chamber.
2. Description Of The Related Art
Interrupters and circuit breakers in medium or high voltage power lines or cables often include casings in which the switch contacts are housed for relative movement between a position in contact with each other, corresponding to the power line being closed, and a position spaced apart from each other, corresponding to the line being open. These casings are filled with a dielectric fluid in which the switch contacts are immersed, and that assists current breaking by extinguishing the arc that might remain after the switch contacts have separated from each other. Many different fluids (such as air, oil, nitrogen, etc.) have been proposed in the past, but nowadays it is common to use sulfur hexafluoride (SF6), which has good dielectric properties and is therefore well adapted for this purpose. Even so, the use of that gas needs to be limited, because it has the drawbacks that its decomposition products are toxic and corrosive, and it contributes to the greenhouse effect. Accordingly, there may be an incentive to use vacuum switch chambers, which are also employed in some circuit breakers, the switch contacts being internal components of these chambers, which are also most effective in quenching arcing currents; however, their use in today's interrupters cannot be considered without further modification for reasons of cost, because the vacuum switch chambers that would need to be employed in these interrupters would be too burdensome in terms of the materials and dimensions that would have to be adopted in order that they could satisfy various electrical and dielectric requirements, such as the ability to withstand lightning strikes.